This invention relates to newly identified polynucleotides, polypeptides encoded by such polynucleotides, the use of such polynucleotides and polypeptides, as well as the production of such polynucleotides and polypeptides. More particularly, the polypeptide of the present invention is human Oxalyl-CoA Decarboxylase.
Evidence suggests that the formation of calcium-oxalate stones in the urine is dependent on the saturation levels of both calcium and oxalate, thus, management of one or both of these ions in individuals susceptible to stone formation in the urinary tract (urolithiasis) appears important. Urolithiasis is a common urinary tract problem afflicting more than 10% of the U.S. population (Sierakowski, R. et al., Invest. Urol., 15:438-441 (1978)). Urinary tract stones are usually classified according to their composition, with the most frequently encountered (70%) being the calcium stone which is composed of calcium oxalate alone or calcium oxalate mixed with calcium phosphate. Although precipitation of calcium oxalate depends on a urine saturated with both calcium and oxalate ions in a meta-stable state, it has been argued that the oxalate ion concentration is more significant in the formation of urinary calcium oxalate stones.
The majority of oxalate in plasma and urine is derived from the endogenous metabolism of ascorbic acid, glyoxylate, and to a lesser degree, tryptophan (Nath, R. et al., Pergamon Press, pp. 55-58 (1984)). In addition, between 10% and 20% of the urinary oxalate is absorbed from the diet, especially through ingestion of leafy vegetables and plant materials. Fortunately, most dietary oxalate appears to be bound by intraluminal calcium and is excreted as an insoluble salt. Thus, there is an inverse relationship between ingested calcium and absorbed oxalate. (Ernest, D. L., et al., Gastroenterology, 66:1114-1122 (1964)).
Either abnormal synthesis or hyper-absorption of oxalate can lead to a serious condition referred to as hyperoxaluria (Liedtke, R. R. et al., Urol. Res., 16:188-189 (1988)). Although this condition may have a genetic basis, the vast majority of cases remain idiopathic (Nath, R. et al., Pergamon Press, pp. 55-58 (1984)). Whether the underlying cause is a disturbance in calcium metabolism or merely increased levels of oxalate there is a strong association between increased levels of urinary oxalate and calcium oxalate stone disease in man.
The basis of stone formation in the urinary tract and ways to treat this disorder has recently been the subject of intensive study. A plant-derived oxalyl-CoA decarboxylase gene has been inserted into human cells as a means of lowering plasma and urinary oxalate concentrations. The oxalyl-CoA decarboxylase gene has been cloned from bacterium Oxalobacter formigenes. Lung, H. Y. et al., Am. J. Kidney Dis., 17:381-5 (1991).
Accordingly, an enzyme that lowers the oxalate levels in the plasma, and subsequently the urine, would decrease the incidence of calcium oxalate stone formation.
In accordance with one aspect of the present invention, there is provided a novel mature polypeptide, as well as biologically active and diagnostically or therapeutically useful fragments, analogs and derivatives thereof. The polypeptide of the present invention is of human origin.
In accordance with another aspect of the present invention, there are provided isolated nucleic acid molecules encoding a polypeptide of the present invention including mRNAs, DNAs, cDNAs, genomic DNAs as well as analogs and biologically active and diagnostically or therapeutically useful fragments thereof.
In accordance with yet a further aspect of the present invention, there is provided a process for producing such polypeptide by recombinant techniques comprising culturing recombinant prokaryotic and/or eukaryotic host cells, containing a nucleic acid sequence encoding a polypeptide of the present invention, under conditions promoting expression of said protein and subsequent recovery of said protein.
In accordance with yet a further aspect of the present invention, there is provided a process for utilizing such polypeptide, or polynucleotide encoding such polypeptide for therapeutic purposes, for example, preventing calcium-oxalate stone formation and hyperoxaluria.
In accordance with yet a further aspect of the present invention, there is also provided nucleic acid probes comprising nucleic acid molecules of sufficient length to specifically hybridize to a nucleic acid sequence of the present invention.
In accordance with yet a further aspect of the present invention, there are provided antibodies against such polypeptides.
In accordance with still another aspect of the present invention, there are provided diagnostic assays for detecting diseases or susceptibility to diseases related to mutations in the nucleic acid sequences encoding a polypeptide of the present invention.
In accordance with yet a further aspect of the present invention, there is provided a process for utilizing such polypeptides, or polynucleotides encoding such polypeptides, for in vitro purposes related to scientific research, for example, synthesis of DNA and manufacture of DNA vectors.
These and other aspects of the present invention should be apparent to those skilled in the art from the teachings herein.